Overall objectives of the total project: To continue studying the regulation of the synthesis of mating type--specific, cell surface glycoproteins in the yeast Hansenula wingei and to develop the genetics of this yeast system. Preliminary genetic studies indicated that there were only a few linkage groups and recent cytological observations corroborated these genetic studies-- H. wingei has only 4 chromosomes. Therefore mapping the 4 linkage groups should be straightforward. Construction of the chromosomal maps is necessary for any genetic studies of the regulation of glycoprotein mating factors. These mating factors define the specificity of the first step in conjugation, that of cellular recognition. The mating factors are complementary and form a neutralized complex in vitro. Neither mating factor is synthesized in the diploid but several ways have been discovered to induce their synthesis. This induction of the haploid mating factors in the diploid could be governed by either genetic or physiological parameters and it is the purpose of future studies to distinguish between these two possibilities.